Fiber optic communication systems currently employ switching systems to route signals at central office switching centers. These electro-optic systems rely on converting the light output from each "incoming" fiber into electrical form, extracting the data content in the resultant electrical signal, then utilizing conventional electrical switches to route the data content to a modulatable optical source that is coupled to a"destination" optical fiber. This detection, switching, and remodulation process is expensive, complex, power consuming, and subject to component failure.
Alternate "All Optical" switching systems, employing mechanically actuated bulk optic and MEMS fabricated devices, currently exist. These devices utilize electromagnetic, piezoelectric and electrostatic actuators to physically move prisms, mirrors and portions of optical fibers to affect switching of signals between optical fibers. In addition, fiber-to-fiber switches employing Grating Waveguides, Rowland Circle Gratings, and planar gratings, permit dedicated switching based on optical wavelength.
Cascaded binary tree configurations, employing switchable optical couplers using electrostatically variable index material, (Lithium Niobate and polymers), as well as Mach Zender interferometers utilizing thermoelectric heaters to affect unbalance, are also currently state of the art.
Many of the MEMS switches employ a space-beam deflection system similar to the electrical "Cross Bar" switch common in telephone system. This approach requires that the number of mirrors for a given input/output port count be determined by the square of the port count figure. The overwhelming number of mirrors dictated by this high port-count switching approach exceeds that which can be produced with any realistic process yield, and survive any reasonable operating period.
Except for some of the MEMS electrostatically actuated devices, none of the above methods of optical switching meets the requirements currently being specified for high fiber port count, (up to 1024 by 1024) Optical Cross Connect switches. Problems of cost, reliability, insertion loss, polarization sensitivity, isolation, wavelength dependence, power consumption, and in some instances, switching speed, either individually or collectively mitigate against their use. Accordingly, what is needed is a system and method for overcoming the above-identified issues under the constraint of a simple CMOS-compatible fabrication process.
An optical mirror system design is desired that has high-resolution 2-D scanning capability and deflection capability, made with a surface-micromachining process. In order to achieve high-resolution, large mirror size and rotation angles are necessary.
The present invention addresses such a need.